Spray foams are widely used as building insulation materials due to their excellent thermal insulation, fire resistance, and mechanical properties. The foams are commonly grouped as either “open cell” foams or “closed cell” foams depending on whether the cells in the foam are completely closed. Spray polyurethane foams (SPFs) made from polyurethane (PUR) are used in both open cell and closed cell foams, while spray isocyanurate foams are made from polyisocyanurate (PIR), which is normally used to make dense closed cell foams. Spray foam insulation is often formed as the polymerizing reactants are being sprayed directly into the building envelope to be insulated, usually with the help of a blowing agent.
Modern building codes require spray foams to pass fire tests such as the well-known ASTM E-84 test or the Appendix X test. These tests put strict limits on such characteristics as the flame spread and smoke development characteristics of a spray foam when the spray foam is exposed to fire. Passage of these tests is important for enabling widespread commercial use of a spray foam product. However, these tests are stringent, and fire retardants may be added to the foam formulation to improve the fire performance of a foam, or other measures may be taken to improve the fire retardancy of a foam. For example, intumescent coatings may be applied to SPFs, adding cost and complexity to the installation process.